Coating fragile objects made from hydrated alginate or hydrocolloid materials



Patented Dec. 30,, 1952 2,623,913 CQATiNG ,FR'AGI'LE OBJECTS" i ftoM HYDRATED ,ALGINATE OR HYDROC OL- L911) MATERiALS David N. Lawrence, New York, N. Y.

No Drawing. Application February 13 1951, Serial No. 210,783

15 Claims (01. 260-752) This invention relates to protective coatings; and in particular is directed to novel compositions for, and method of, protecting the surfaces of delicate or fragile objects such as shaped articles made from hydrated hydrocolloid or alginate materials or delicate or fragile material or manufactured objects.

When hydrocolloid Or alginate materials are mixed with water they form plastic masses which are employed in making impressions of delicate members of the body or intricately shaped articles. For example, such plastic masses are used by dentists and ophthalmologists to make impressions which serve as molds from which plaster reproductions are made. These reproductions, as that of a tooth, or an eye, are used as the bases for the formulation of inlays, metal caps, crowns, bridges, dentures, or artificial eyes, hands, parts of the face, etc.

Hydrated alginate or hydrocoloid materials, however, quickly undergo changes in dimensions because of the rapidity with which they lose or absorb water. This is a great disadvantage because it is imperative immediately after taking an impression with such a mass to pour the plaster in order to be certain that the plaster cast is a faithful reproduction of the tooth, body member, or article which it simulates. Another disadvantage in using suchimpression materials resides inthe fact that when the plaster is poured againstthe moist or uncoated surfaces thereof the resultant shapes or models are rough and coarse. It has been recognized that it would be desirable, if possible, so to treat such impressions as to render them structurally and. dimensionally stable. Up to now,- however, it has beenimpossible properly to treat such impressions inorder to preserve the fidelity thereof. Until the present inventionit has been impossible, successfully andconsistently, to plate the same with metal in an effort at least to stabilize the surface of the impression so that the impression may be used to obtain faithful reproductions of the details of the impression surface. Such failure is due to the fact that the surfaces of theimpression are quickly attacked and alteredby the acids, alkalis, or salts of the plating bath.

I have discovered that it is possible so to treat an impression made of alginate or hydrocolloid materials that the surfaces thereof can be rendered capable of receiving a metallic plate, of excellently stable and faithful dimensions. The impression so plated may then be set aside until some conyenient time is reached in the laboratory, and a metal covered plaster cast made therefrom in due course.

Accordingly, it is one of the principal objects of this invention to provide means whereby an impression of an object made from hydrocolloid or alginate impression materials may be treated with a protective coating so as to obtain a stable and faithful impression of such article.

Another object of the invention is to treat an impression made of hydrocolloid or alginate materials so as to render the surface thereof capable of receiving an adherent coating of a metallicplate. H a

It is also known that delicate materials or objects of great fragility such as leaves, flowers, feathers or any soft organic matter, or paper, lace, cloth and the like are exceedingly difficult to coat with metal by electroplating processes. These materials are quickly attacked by the highly chemically reactive acids, alkalis or salt solutions of the customary plating baths.

I have discovered that it is possible to coat the surfaces of such materials of great fragility and delicacy with a composition that is exceedingly resistant to the aforesaid chemical reaction; that such protective surfacing preserves the delicate delineations thereof with great fidelity; and that it is possible to deposit on such protective surfacing a layer of electrodepositedmetal, thereby to obtain electroplated leaves, flowers, lace, etc, which faithfully reflect the delineations and contours of the original object.

In its fundamental aspect the aims of my invention are achieved by coating the objects with a modified solution of a wax that dries rapidly after application to the surface and forms an extremely smooth, highly adherent, exceedingly thin; protective film or coat that is resistant to water and chemical reaction, which protective film may be treated to form a surface on which a metallic plate may be electrodeposited.

Illustrative examples of compositions producing such protective coating and the manner of applying them are as follows:

Example 1 solution dries in about 30 seconds, leaving the solutes deposited as an extremely smooth, highly adherent, very thin film having a thickness of about 0.0001 inch. The impression thus coated or filmed with the wax is thereby preserved with faithful accuracy as to the dimensions thereof.

I then take the impression, the surface of which has been protected as above described, and dust the surface of the impression, treated as above, with a metallic powder such as copper, silver, iron or any other appropriate conductive material, or combination of such metallic powders or materials. I then place the impression with the metallized surface, as prepared, in an electroplating bath and deposit thereon a layer of copper, silver, gold or any other appropriate plating metal. Thereafter, the plated impression is used as a mold into which I pour the customary plaster to form a cast. After the plaster has set, the hydrocolloid is removed or peeled away, leaving the cast or stone model with the .metallic plate covering the same. Such stone model is a faithful reproduction of the original tooth which it simulates. In a similar manner any other object may be reproduced in a cast or stone model by taking an impression of the original object and following the steps above described. In the case of delicate or fragile articles such as leaves, flowers, feathers, paper, lace, etc., I coat the same with the solution above described. In this way the surface thereof is filmed with the protective coating of the solution. I then dust the surface thereof with a metallic powder in similar manner to that above described, after which the same is electroplated with an appropriate metal.

Example 2 I dissove four (4) ounces of white bleached beeswax, one (1) 'ounce of pure rubber, one (1) ounce of asphalt, one-half (0.5) ounce of stearic acid, six (6) ounces of glyceryl phthalate, six (6) ounces of dibutyl phthalate, in one (1)- gallon of a lacquer solvent.

This composition is applied to impressions made from alginate or hydrocolloid impression materials or leaves, flowers, etc., in the same way as described in Example 1.

The impressions or objects thus coated are treated in the same way as-those described in Example 1; and ultimately plated as therein described.

I have found that it is possible to prepare solutions using from two (2) to six (6) ounces of the white bleached beeswax per gallon of solvent which may be the lacquer solvent or high flash naphtha above described for benzene, toluene, xylene, solvent naphtha or any other appropriate solvent. A greater amount of the wax may produce too heavy a film.

The asphalt used in the preparation of the solution may range in quantity from one-half (0.5) to one and one-half (1.5) ounces, while the stearic acid used may range in amount from onequarter ounce to three-quarters 4) ounce.

The glyceryl phthalate may be used in an amount of from four (4) to eight (8) ounces per gallon of solvent.

The rubber may be omitted from the solution but I have found that it is preferable to incorporate same in an amount of from one-half /2) to one and one-half (1 /2) ounces per gallon of the solvent used.

- 'I have also found that in place of the dibutyl phthalate, which is present in an amount of from it is preferable to use the same.

four (4) to eight (8) ounces per gallon of solvent, it is possible to use other plasticizers employed in lacquer formulations, such other plasticizers being butyl stearate, diethyl tartarate, dimethyl phthalate, diethyl phthalate, dibutyl tartarate, butyl orthobenzoylbenzoate, triphenylphosphate, diamylphthalate, tricresylorthobenzoylbenzoate, tributylphosphate, and camphor.

The rubber, described in Examples 1 and 2, may be omitted from the formulation but I find The rubber when used may be incorporated in an amount of 0.5 to 1.5 ounces per gallon of the solvent used.

I have found that a truer, smoother stone model or cast will be made from the impression prepared from hydrocolloid or alginate materials treated with the above described Wax solution. even without electroplating the same.

It is to be understood that the foregoing discussion and examples are merely illustrative of the principles thereof; and accordingly that the appended claims are to be construed as defining the invention within the spirit and scope thereof.

I claim:

1. A composition adapted to provide a smooth, thin, adherent, chemically resistant coating on the surface of shaped objects made from hydrated alginate or hydrocolloid materials, thereby to preserve the physical and dimensional stability thereof which comprises a solution of one 1) gallon of a volatile solvent and from two (2) to six (6) ounces of white beeswax, 0.5 to 1.5 ounces of rubber, from 0.5 to 1.5 ounces of asphalt, from .25 to .75 ounce of stearic acid, from four (4) to eight (8) ounces of glyceryl phthalate, and from four (4) to eight (8) ounces of a lacquer plasticizer.

2. A composition adapted to provide a smooth, thin, adherent, chemically resistant coating on the surface of shaped objects made from hydrated alginate or hydrocolloid materials, thereby to preserve the physical and dimensional stability thereof which comprises essentially one (1) gallon of volatile solvent, four (4) ounces of White bleached beeswax, one (1) ounce of pure rubber, one (1) ounce of asphalt, one-half (0.5) ounce of stearic acid, six (6) ounces of glyceryl phthalate, and six (6) ounces of dibutyl phthalate.

3. A method of protecting the surfaces of delioate fragile materials or shaped articles made from hydrated alginate or hydrocolloid materials, thereby to preserve the physical and dimensional stability thereof which comprises coating the said surfaces with a solution of from two (2) to six (6) ounces of white bleached beeswax, from 0.5 to 1.5 ounces of asphalt, from .25 to .75 ounce of stearic acid, from four (4) to eight (8) ounces of glyceryl phthalate, and from four (4) to eight (8) ounces of a lacquer plasticizer in one (1) gallon of a volatile solvent, thereby to produce a smooth, thin, adherent, mechanically resistant coating on said surfaces. I

4. A method of protecting the surfaces of delicate, fragile materials or shaped articles made from hydrated alginate or hydrocolloid materials, thereby to preserve the physical and dimensional stability thereof which comprises coating the said surfaces with a solution of from two (2) to six (6) ounces of white bleached beeswax, from 0.5 to 1.5 ounces of rubber, from 0.5 to 1.5 ounces of asphalt, from .25 to .75 ounce of stearic acid, from four (4) to eight (8) ounces of glyceryl phthalate, and from four (4) to eight (8) ounces of a lacquer plasticizer in one (1) gallon of a volatile solvent,

thereby to produce a smooth, thin, adherent, mechanically resistant coating on said surfaces.

5. A composition adapted to provide a smooth, thin, adherent, chemically resistant coating on the surface of a delicate, fragile article or shaped objects made from hydrated alginate or hydrocolloid materials thereby to preserve the physical and dimensional stability thereof which comprises a solution of about one (1) gallon of high flash naphtha and from two (2) to six (6) ounces of white beeswax, from 0.5 to 1.5 ounces of asphalt, from 0.25 to 0.75 ounce of stearic acid. from four (4) to eight (8) ounces of glycerylp'hthalate, and from four (4) to eight (8) ounces of a lacquer plasticizer.

6. A composition adapted to provide a smooth, thin, adherent, chemically resistant coating on the surface of a delicate, fragile article or shaped objects made from hydrated alginate or hydrocolloid materials thereby to preserve the physical and dimensional stabiilty thereof which comprisesa solution of about one (1) gallon of high flash naphtha and from two (2) to six (6) ounces of white beeswax, from 0.5 to 1.5 ounces of rubbar, from 0.5 to 1.5 ounces of asphalt, from 0.25 to 0.75 ounce of stearic acid, from four (4) to eight (8) ounces of glycerylphthalate, and from four (4) to eight (8) ounces of a lacquer plasticizer.

7. A composition in accordance with claim 2 wherein the volatile solvent is high flash naphtha.

8. A method in accordance with claim 3 wherein the volatile solvent is high flash naphtha.

9. A method in accordance with claim 4 wherein the volatile solvent is high flash naphtha.

10. A method of protecting the surfaces of delicate, fragile materials or shaped articles made from hydrated alginate or hydrocolloid materials, thereby to preserve the physical and dimensional stability thereof which comprises coating the said surfaces with a solution of about 2 to 6 ounces of white beeswax, about one (1) ounce of rubber,

about one (1) ounce of asphalt, about one-half (0.5) ounce of stearic acid, about six (6) ounces the.

12. A method in accordance with claim 11 wherein the lacquer plasticizer is dibutyl phthalate. 13. A method of protecting the surfaces of delicate, fragile materials or shaped articles made from hydrated alginate or hydrocolloid materials, thereby to preserve the physical and dimensional stability thereof which comprises coating the said surfaces with a solution of about four (4) ounces bf'white beeswax, about one (1) ounce of rubber,

about one (1) ounce of asphalt, about one-half (0.5) ounce of stearic acid, about sigg"(6) ounces of glycerylphthalate, and six (6) ounces of a ,lacquer plasticizer dissolved in one (1") gallon of la volatile solvent.

"5-14. A method in accordance with claim 13 wherein the volatile solvent is high flash naphtha.

' 15. A method in accordance with claim 14 wherein the lacquer plasticizer is dibutyl phthalate.

. DAVID N. LAWRENCE.

REFERENCES CITED 1 The following references are of record in the file of this patent: 1

UNITED STATES PATENTS Number Name Date 1,897,034 Harrison et a1 Feb. 14, 1933 1 2,030,055 Dixon ..Feb. 11, 1936 g '2,039,228 Kratz et a1. Apr. 28, 1936 2,057,289 Luce et al Got. 13, 1936 2,118,521 Pickens May 29, 1938 2,178,663 Harrison 'Nov, '7, 1939 

3. A METHOD OF PROTECTING THE SURFACES OF DELICATE FRAGILE MATERIALS OR SHAPED ARTICLES MADE FROM HYDRATED ALGINATE OR HYDRCOLLOID MATERIALS, THEREBY TO PRESERVE THE PHYSICAL AND DIMENSIONAL STABILITY THEREOF WHICH COMPRISES COATING THE SAID SURFACES WITH A SOLUTION OF FROM TWO (2) TO SIX (6) OUNCES OF WHITE BLEACHED BEESWAX, FROM 0.5 TO 1.5 OUNCES OF ASPHALT, FROM .25 TO .75 OUNCE OF STEARIC ACID, FROM FOUR (4) TO EIGHT (8) OUNCES OF GLYCERYL PHTHALATE, AND FROM FOUR (4) TO EIGHT (8) OUNCES OF A LACQUER PLASTICIZER IN ONE (1) GALLON OG A VOLATILE SOLVENT, THEREBY TO PRODUCE A SMOOTH, THIN, ADHERENT, MECHANICALLY RESISTANT COATING ON SAID SURFACES. 